Mesoproterozoic mafic dyke swarms are extensively developed in the Western Shandong, the east of the North China Craton, which intruded the Early Precambrian crystal basement. The dorminant orientation of these mafic dykes is nearly N-S trending. The mafic dyke swarms in the Western Shandong belong to LREE enrichment magmatic rocks, and are formed in a continental rift environment according to petrology and geochemistry of these mafic dykes. The flow structures and geometry evidences of the dykes indicatethat the magma source of these dykes intruded the pre-existingtensional rupture . The dyke swarms in the Western Shandong intruded from North to South. Angles between the long axis orientations of magnetic fabric textures and the middle line of dykes suggest that the flow direction of these dykes is from North to South. Further it indicate that the dykes intruded fromNorth to South. These flow structures, geochemistry and magnetic fabric textures suggest that magma come from enriched mantle magma source beneath the Yanliao-Zhongtiao aulacogens based on space-time relationship between the mafic dyke swarms and Yanliao-Zhongtiao aulacogens.

To predict the distribution of the favorable volcanic facies belts of Yingcheng Group in Xujiaweizi Depression, it's necessary to analyze the factors to control the reservoir capabilities of the volcanic rocks. Observation of cores and thin sections indicates that primary pores are the basic reservoir space of the volcanic rocks, while secondary pores have important influence. Through statistics of the pore types and comparison of the physical properties of the volcanic rocks, the authors find that the control factors of the volcanic reservoir capabilities are lithofacies, fractures, and dissolution by the acidic fluid. The formations that have been dissoluted under the unconformities on top of the volcanic edifices near the main faults will be the most important exploration targets.